Known power electronic components, for example semi-conductor switching elements or the like can be vulnerable to thermal problems due to the amount of thermal energy generated by the current flowing through them. As power electronic devices reach larger and larger power values and consequently dissipate thermal energy, the efficiency of the cooling systems to sustain reliability of such power electronic devices becomes more and more important. Further, the tendency towards achieving higher power densities, such as more compact power electronic devices being able to handle an equal or larger amount of power than before, as well as less space for the cooling system and for the air flow, pose continuous challenges to the design and efficiency of the employed cooling systems.
Moreover, it is desired that cooling systems for modern electrical products have higher performance at a lower price. Performance and price can be positively correlated, which is a constant challenge for design engineers of electrical products.
One option for providing cooling of power electronic devices, for example IGBT (insulated gate bipolar transistor) based components (e.g. press-packs) and/or devices that can be under a voltage with a current flowing through them, is water cooling systems using de-ionized water. However, these systems can be bulky and heavy since they can specify use of a de-ionization unit. Air cooling is another way of providing a simple and inexpensive way of cooling such power electronic devices, but it is limited by the poor thermo-physical properties of air, which has a low thermal conductivity, as well as a low specific heat.
At present, one way of providing an efficient cooling system for power electronic devices is to provide a two-phase cooling circuit. Such a cooling circuit brings a liquid into thermal contact with the heat emitting device. The liquid is heated by the dissipated heat and reaches a boiling temperature. As the temperature of the liquid will not rise above the boiling temperature, the temperature of the liquid and therefore the temperature of the electronic device is kept at a temperature of the boiling point of the liquid as a maximum. The vapour of the liquid is then guided through a conduit—a vapour riser pipe—to a condenser. Within the condenser the vapour is changed into liquid by emitting or releasing heat. For example, in the condenser the heat is emitted to a coolant medium, such as air at ambient temperature. The vapour thus returns to its liquid phase. The condenser and the evaporator unit can be connected via a second line—downcomer pipe—in order to feedback, supported by gravity, the condensed vapour as liquid again to the liquid reservoir of the evaporator unit.
If two-phase cooling circuits are to be used for cooling multiple independent power components their reliability as well as their cooling efficiency should be increased. Further, due to the competitive nature of the market for such cooling circuits, reducing the cost of production is desired.
The U.S. Pat. No. 4,733,331 discloses a heat dissipation mechanism for power semiconductor elements that can be stacked together with associated evaporation blocks to form a column. The evaporation blocks can be fluidly connected, via tubes including electrically insulating connective elements, to first dissipator bodies, or condensors. The latter can be located vertically below second dissipator bodies, in order that the coolest air rising due to natural convection serves first for the cooling of the semiconductor elements via the respective associated first dissipator bodies. A ventilator (e.g., ventilation means) can be arranged to provide forced ventilation along a horizontal stacking direction.
In one aspect, a modular cooling system for cooling a plurality of power electronic components, the cooling system including a plurality of cooling modules and a clamping arrangement is provided. Each of the cooling modules includes, respectively, an evaporator unit adapted for receiving heat from a corresponding one of the power electronic components, the evaporator unit having an inlet for receiving a liquid cooling fluid, an evaporator body for evaporating the cooling fluid by the heat, and an outlet for letting out the vaporized cooling fluid; a condenser having an inlet for receiving the vaporized cooling fluid, a condenser body for condensing the cooling fluid, and an outlet for letting out the condensed liquid cooling fluid; a first pipe system connecting the outlet of the evaporator unit with the inlet of the condenser; and a second pipe system connecting the outlet of the condenser with the inlet of the evaporator unit. Each of the cooling modules forms a respective individual cooling fluid circuit separate from the cooling fluid circuits of the other cooling modules of the cooling system, and the clamping arrangement is adapted for holding and pressing an alternating stack in which the evaporator units can be stacked alternately with the power electronic components in a stacking direction. Further, the condenser of each cooling module includes at least one coolant medium passageway for an external coolant medium, wherein the at least one coolant medium passageway defines a flow direction for the external coolant medium transverse to the stacking direction of the alternating stack.
Electrically insulating portions in the form of solid layers can be used between adjacent, or neighbouring, condensers of separate cooling modules. This arrangement provides an easy to assemble, cost effective and reliable solution for electrically insulating a plurality of cooling modules from each other, and avoids a specifying an arrangement that includes electrically insulating sections on the pipes between the evaporating units and the condensers.
In another aspect, a power electronic unit including the aforementioned modular cooling system and a plurality of the power electronic components is provided. The clamping arrangement holds and presses the alternating stack in which the evaporator units can be stacked in alternation with the power electronic components in the stacking direction.
In yet another aspect, a use of the aforementioned modular cooling system or power electronic unit for cooling the plurality of the power electronic components is provided. The clamping arrangement holds and presses together the alternating stack in which the evaporator units can be stacked in alternation with the power electronic components in the stacking direction.
In yet another aspect, a method of cooling a plurality of power electronic components by a modular cooling system, the cooling system including a plurality of cooling modules and a clamping arrangement is provided. Each of the cooling modules includes, respectively, an evaporator unit having an inlet, an evaporator body and an outlet; a condenser having an inlet, a condenser body, an outlet, and at least one coolant medium passageway; a first pipe system; and a second pipe system. The clamping arrangement holds and presses an alternating stack in which the evaporator units can be stacked alternately with the power electronic components in a stacking direction. The method includes transferring heat from one of the power electronic components to a corresponding one of the evaporator bodies; evaporating a liquid cooling fluid inside of the evaporator body by the heat from the power electronic component; guiding the vaporized cooling fluid via the first pipe system from the evaporator's outlet to the condenser's inlet; condensing the vaporized cooling fluid to a liquid phase by removing heat from the vaporized cooling fluid in the condenser body; and guiding the liquid cooling fluid via the second pipe system from the condenser outlet to the evaporator inlet. The cooling fluid is circulated in a fluid cooling circuit including the evaporator body, the first pipe system, the condenser body and the second pipe system of the respective cooling module, whereby the fluid cooling circuit is an individual fluid cooling circuit separate from the fluid cooling circuits of the other cooling modules, and whereby removing heat from the vaporized cooling fluid in the condenser body includes guiding an external coolant medium in a flow direction transverse to the stacking direction of the alternating stack.
Further aspects, advantages and features of the present disclosure can be apparent from the dependent claims, the description and the accompanying drawings.